<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>

    <style>
        .box1 {
            width: 100px;
            height: 100px;
            background: red;
            border: 10px solid green;
            padding: 10px;
        }
        .box2 {
            width: 50px;
            height: 50px;
            background: purple;
        }
        .box3 {
            width: 100px;
            height: 100px;
            background: yellow;
            /* 上，右，下，左 */
            margin: 10px 20px 30px 40px;
            /* margin-top: 10px;
            margin-left: 20px; */
        }
    </style>
</head>
<body>
    <div class="box1">
        <div class="box2">

        </div>
    </div>
    <div class="box3">

    </div>
</body>
</html>